The subject of the invention is an actuator for gates, doors and any other similar barriers for closing entrances or openings with at least one wing (rotating or sliding), or the like, the said actuator comprising an arm or half-arm or so-called actuator arm, hinged with its rear end to a fixed support in an angularly displaceable manner, being displaceable by means of an electric motor and a reduction unit. The arm can be an articulated arm having a so-called drawing arm articulated with its front end to the wing of the door, and with its rear end, by means of an intermediate folding articulated joint, to the front end of the actuator arm.
DE-U-295 13 302 discloses an actuator for a window with a rotating wing. The actuator comprises a foldable arm, which is hinged to a fixed support on one side and to the wing on the other side. An actuating motor and a reduction unit are arranged in the half-arm hinged to the fixed support and are operatively connected to the intermediate articulation between the two half-arms.
DE-A-197 24 439 discloses an actuator for a bus door, wherein a clutch system is provided between the door swinging pivot and the coaxial gear to enable the door to be freely rotated in case of emergency.
The purpose of the invention is to provide an actuator which, as a whole, presents smaller overall dimensions, and the arm of which affords greater sturdiness so that it can be used as a stay for blocking the wing in the closed position, whilst it may also be installed on supports, for instance, on supporting posts of small dimensions, in any case preventing damage if the actuator half-arm were to be subjected to rotational stress exerted by excessive external forces and enabling its angular displacement by the said external forces in the direction of opening and closing of the wing, at the same time making possible release of the actuator half-arm from the respective operating motor for easy manual emergency displacement of the wing.
According to one characteristic of the invention, the above purpose is achieved by the fact that the electric actuating motor and the associated reduction unit are carried by the arm, preferably by the actuator half-arm and are preferably, housed in a correspondingly shaped and sized recess of the arm and preferably of the actuator half-arm itself.
According to a preferred embodiment of the invention, the electric motor operates, by means of the reduction unit, a manoeuvring worm screw which is carried by the actuator half-arm and engages with a corresponding helical gear coaxial to the swinging axis of the actuator half-arm, and is blocked, in a way so that it cannot turn, to the fixed support of the aforesaid half-arm itself.
According to another characteristic of the invention, the helical gear is mounted on the fixed support of the actuator half-arm by means of a torque-limiting device regulated in such a way as to enable rotation of the helical gear together with the associated worm screw, and hence together with the actuator half-arm, when the latter is subjected to rotational stresses exerted by external forces greater than a pre-set maximum allowable stress of the actuator half-arm itself.
Preferably, according to a preferred embodiment of the invention, the torque-limiting device is also used to disengage the actuator half-arm intentionally from its fixed support and so to enable its free and. easy rotation about its swinging axis when it is desired to displace the wing manually about its oscillating axis in cases of emergency, for example, in the case of absence of electric current. For this purpose, according to the invention, the torque-limiting device set between the helical gear and the fixed support of the actuator half-arm, as well as being disengageable automatically by the action of a pre-set maximum safety moment exerted on and exerted by the actuator half-arm, is associated to releasing means for pre-arrangement of the emergency manoeuvre which can be operated manually, for example by means of a suitable, possibly ciphered, wrench and are designed to disengage and deactivate the aforesaid torque-limiting device.
Both the torque-limiting device and the releasing means associated thereto for its manual disengagement in the event of emergency may be built in a very wide variety of ways suited for the purpose.
According to a preferred embodiment of the invention, the helical gear is fixed to a gear casing on which the rear end of the actuator half-arm is mounted, in such a way that it is free to turn, the said gear casing being in turn mounted, so that it is free to turn and is axially sliding, on a hinge pin that is coaxial with the swinging axis of the actuator half-arm and fastened to the fixed support of the said half-arm, whilst the torque-limiting device is made up of two toothed annular disks, which are set one on top of the other and are coaxial with the swinging axis of the actuator half-arm, one of the disks being fastened to the fixed support of the said half-arm, and the other being fixed to the gear casing, the said annular disks meshing together by means of their ring gears which are set facing head-on to one another, the said ring gears being provided with radial teeth having inclined sides, there being provided an engaging spring which exerts axial thrust on the gear casing in the direction of mutual engagement of the two toothed annular disks set on top of one another, consequently blocking the helical gear, in such a way that it is not able to turn, to the fixed support of the actuator half-arm, but enabling mutual disengagement of the two toothed disks by means of a corresponding movement of axial yielding of the gear casing against the action of the engaging spring, and hence enabling jerking rotation of the helical gear about the hinge pin as a result of a maximum pre-set torque exerted from outside, for example manually, on the actuator half-arm, and from this, by means of the worm screw, on the helical gear itself.
To enable manual emergency angular displacement of the wing and the corresponding oscillating movement of the actuator half-arm on its fixed fulcrum, the two toothed annular disks of the above-described torque-limiting device are disengaged from one another, for this purpose displacing the gear casing axially on the hinge pin against the action of the engaging spring and by manually controlled releasing means, and keeping the aforesaid casing in a position of disengagement of the torque-limiting device, thus enabling the gear casing, and hence the helical gear, to rotate freely together with actuator half-arm about the swinging axis of the latter.
Also the above mentioned releasing means for manual disengagement of the torque-limiting device may be built in any suitable way whatsoever. In a preferred example of embodiment of the invention describe above, the aforesaid releasing means for manual emergency disengagement of the torque-limiting device consist of a face cam mounted so that it can, turn manually between the gear casing or a part connected to the latter, consisting in particular of a part of the rear hinged end of the actuator half-arm, and the head end of the hinge pin fixed to the support of the actuator half-arm, the said cam presenting a profile such as to enable, in one first angular position of the said cam, mutual engagement of the two toothed disks of the torque-limiting device by the action of the respective engaging spring, whilst it displaces and withholds, in a second angular position, the gear casing axially on the hinge pin and against the action of the engaging spring in a position of disengagement of the torque-limiting device.
In the preferred embodiment of the invention described above, both the automatic disengagement and the intentional disengagement by manual emergency means for releasing the torque-limiting device set between the helical gear and the fixed support of the actuator half-arm require a limited axial displacement of the gear casing, and hence of the respective hinged rear end of the actuator half-arm, on the fixed hinge pin along the respective swinging axis.
Also this axial displacement of the hinged rear end of the actuator half-arm may be enabled from a constructional standpoint in any suitable manner whatsoever, even by means of corresponding allowances and tolerances. According to an embodiment of the invention, however, for this purpose the intermediate articulated joint for folding of the foldable arm of the articulated actuator or for the fixing to the wing and/or the joint articulating the drawing half-arm to the wing are made like ball-and-socket joints or else like Cardan joints, with at least two mutually orthogonal axes of articulation, one axis being substantially parallel to the axis of oscillation of the wing, and the other axis being transverse to the half-arms, so enabling, when the gear is axially displaced on the hinge pin in order to disengage the torque-limiting device, a corresponding inclination of the actuator half-arm, and hence a corresponding axial displacement of its rear end with respect to the hinge pin itself. For the same purpose, a corresponding ball-and-socket joint or Cardan joint may be provided also between the gear casing and the respective end of the actuator half-arm.